package com.itheima.String;

public class DM09 {
    public static void main(String[] args) {
        String s1 = "Good Good Study ,Day Day Up";
        String s2 = s1.toUpperCase();
        System.out.println(s2);

        String s3 = s2.toLowerCase();
        System.out.println(s3);

        String s4 = s1.trim();
        System.out.println(s4);

        boolean fa = s1.contains("study1");
        System.out.println(fa);

        String name ="柳岩";
        boolean fa2 = name.startsWith("柳");
        System.out.println(fa2);

        boolean fa3 = name.endsWith("岩");
        System.out.println(fa3);

        String[] names = {"张三","张无忌","张三丰","金毛狮王","周芷若"};
        s1 = "good good study , day day up";
        int firstindex = s1.indexOf("o");
        System.out.println(firstindex);
    }
}
